Harper: Two Parasitic Mushrooms 
71 
enlarged and covers the mouths of the gill chambers up to the 
margin of the pileus with a thick coat, pi. lyg, f. B, and pi. 178, 
f. C. The base of the stem is also much thickened and does not 
become hollow. In many cases, there is a solid mass of parasitized 
stem, veil, and gill tissue and no annular gill cavity is formed, but 
often a more or less evident slit appears between the gills and 
veil as in pi. z/p, f. A. This is the cleft observed by Lanzi and 
interpreted by him as connected with the formation of a ring. 
The gills of the host plants attain nearly normal size and some- 
times produce spores but are more or less parasitized. The sub- 
stance of the pileus appears to be least affected and is not greatly 
thickened in the plants observed. The mycelium of the parasite 
causes the greatest deformation in the stem and the fruiting bodies 
are produced from the apex of the stem. This would suggest 
that the mycelium enters the host from beneath, but the method 
b)- which the Copriniis becomes infected is unknown: 
I can offer no suggestion as to the group to which Pilosace 
algericnsis belongs nor to what non-parasitic mushroom it is 
nearest akin. 
Geneseo, Illinois. 
Explanation of Plates CLXXV'II-CLXXIX 
Plate CLXXVII 
Fig. A. Two mature plants of Volvaria Lozveiaita growing from the de- 
formed pileus of Clitocybe nebularis. 
Fig. B. A single carpophore of the parasite showing the volva. 
Fig. C. Two plants of Volvaria plumnlosa taken from dried specimens. 
Fig. D. Form of Clitocybe nebularis with nearly equal stem and dark- 
fuscouJ pileus. 
Plate CLXXVII I 
Fig. A. Large plant of the form of Clitocybe nebularis with thick bulbous 
stem, white pileus, and decurrent gills. 
Fig. B. Small plant with adnate or sinuate gills. 
Fig. C. Deformed Coprinus with a single carpophore of Pilosace algeri- 
ensis growing from the center of the pileus. 
Fig. D. Section of the host showing the depressed pileus with the para- 
site in the center, the enlarged base of the stem, and the thickened veil cover- 
ing the edges of the gills. 
Plate CLXXIX • 
Fig. A. Vertical section of both the host and the parasite. The gill slit 
has been pulled open slightly. Compare with PI. 178, f. D. 
